Wall raising devices (sometimes called “wall jacks”) are used in the construction field, whereby after walls have been framed on the floor or deck, they are then lifted to the desired vertical placement allowing the wall to be secured to the floor.
Wall jacks of the past have been large, awkward to handle, sometimes quite heavy, and a majority of the time have required two people to handle. Various wall jack designs are described in U.S. Pat. Nos. 2,812,077, 3,485,386, 5,833,430 and 6,019,561, the disclosures which are incorporated by reference herein in their entireties.
U.S. Pat. No. 6,019,561 proposes a “collapsible” nylon strap-tubular design. However, the nylon straps do not feed out or retract as easily and freely as cable designs; moreover, the tubular design may not provide the sufficient strength characteristics without considerably more expense in materials. Cables can be affordable, durable and practical; and, therefore, nylon straps are rarely desirable. Further, U.S. Pat. No. 6,019,561 does not consider possible back strap-slap towards the user that may be possible with nylon material failure in heavier-wall erections.
Fabricated cylindrical shafts, such as those of U.S. Pat. Nos. 2,812,077, 3,485,386 and 6,019,561, may not provide the strength either longitudinally, transversely or cross-sectionally in comparison to that of square tubing or U- or C-channeled extensions. Being more prone to collapse, especially for use with higher walls of greater mass and weight, their construction must be of such material as to make them cost prohibitive, or otherwise present a greater hazard to the user. U.S. Pat. No. 5,833,430 proposes wood sections, which are also prone to strength and safety concerns during use.